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CORPECTOMY AUTOGRAFT AND INTERNAL FIXATION OF THE FRACTURED LOWER

VIEWS: 13 PAGES: 12

									E.J.N.S. Vol. 22 No. 2          June 2007                                              81

                       Microsurgical Resection of
                Posterior Petrous Meningiomas: 18 Cases
      Hazem Abul-Nasr, MD, Alaa Abdel-Fattah, MD, Magdy Samra, MD,
                 Basem Ayoub, MD and Walid Raafat, MD
               Department of Neurosurgery, Cairo University

                                      ABSTRACT
In this study a series of 18 patients with meningiomas of the posterior petrous bone had
undergone microsurgical treatment in Nurosurgical Department, Cairo University Hospitals
from February 2000 to May 2005. The patient population consisted of 14 females and 4 males
with a mean age 49.1 years (range 32-61 years). The main symptom on first admission was
diminution of hearing in 61%, tinitus in 38.9% and vertigo in 33% . Physical examination
and audiological testing revealed hearing impairment in 66.7%, gait ataxia in 33.3% and
trigeminal hyposthesia in 27.8%. All patients underwent surgical treatment via a lateral
suboccipital approach. The tumour was found to be attached to the retromeatal dura in
66.7%, premeatal dura in 16.7%, suprameatal dura in 11.1% and one case (5.6%) centered
on IAM with gross intrameatal growth and widening of the IAM. Tumour resection was
categorized into Grade 1 in 27.8%, Grade 11 in 55.6%, Grade 111 in 11.1% and Grade1V in
5.6% according to the Simpson classification system. The site of displacement of the cranial
nerves was predictable in most of the patients depending on the dural origin of the tumour as
depicted on preoperative magnetic resonance imaging studies. However; the exact
relationship of the neurovascular structures in relation to the tumour can only be fully
appreciated intraoperatively. Postoperatively, all patients of Trigeminal pains (16.7%) had
complete resolution . Hearing was preserved in 72% and one of them had mild improvement
(5.6%). Deterioration of hearing occurred in 27.8% and permant facial nerve palsy was
observed in 11.1%. It was concluded that CPA meningiomas require special surgical
management with detailed analysis of the preoperative MR Images to predict the site of
displaced neurovascular structures, careful operative technique with familiarity with the
anatomy, and effective intraoperative nerve monitoring to obtain an optimal functional result.
Keywords: Cerebellopontine angle, meningioma, microsurgery, suboccipital approach.

        INTRODUCTION                              images and as revealed in the surgical
                                                  record.
    Meningiomas represent the second                  Five tumour groups were created:
most common tumour in the CPA, with               retromeatal, premeatal, suprameatal,
a prevalence of 10 to 15% of all CPA              inframeatal, and centered on the
lesions.(3,4,14)   Posterior    petrous           IAM.(12)
meningiomas        refer     to   those               The clinical presentation, as for
meningiomas originating from the                  meningioma as a whole, depends on
posterior surface of the petrous bone,            the site of origin and direction of
the clinical manifestations, surgical             growth. Tumours growing superior to
difficulty and outcomes for the various           the internal auditory meatus commonly
posterior petrous meningiomas are                 present with trigeminal symptoms,
clearly different because of their                whereas those growing alongside the
various locations.(14)                            meatus may present with auditoury and
    These tumours were classified                 facial nerve dysfunction, the latter
according to their site of dural                  being distinctly uncommon with
attachment in relation to the PA as               vestibular     schwannoma.      Those
demonstrated on preoperative MR                   tumours growing inferior to the meatus
                                                  may present with dysfunction of the
E.J.N.S. Vol. 22 No. 2        June 2007                                       82

lower cranial nerves. Symptoms and         remove       the     posterior    petrous
signs secondary to brain stem and          menengiomas.
cerebellar compression, owing to the       The craniotomy was enlarged to the
slow growth rate are a late                foramen magnum, and the cisterna
occurrence.(15)                            magna was opened. A nerve stimulator
Clinical Material and Methods              was used in all cases to identify the
Patient population                         facial nerve. The meningioma’s dural
    A series of 18 patients of posterior   attachment to the posterior pyramid
petrous meningiomas were treated at        was progressively coagulated and
the Neurosurgical Department of Cairo      divided      to     devascularize      the
University hospitals from February         tumour,and this was done carefully to
2000 to May 2005.                          avoid injury to the exiting cranial
    The patients consisted of 14 female    nerves.
and 4 male with a mean age 49.1 years          When the size of the tumour
(ranging from 32 to 61 years). All         precluded safe removal the tumour
patients     underwent     a     general   capsule was opened and the tumour
neurological examination, audiological     was      centrally      debulked      and
testing with pure tone audiography and     devascularized. The capsule was then
speech discrimination score, and           carefully      dissected     from      the
neuroimaging examinations (CT or           surrounding cranial nerves, the brain
MR imaging). Surgery was performed         stem, the superior cerebellar artery
after general anasthesia had been          (superior and medial), the anterior
induced and the operating microscope       inferior cerebellar artery (medial), and
and microsurgical instrumentation          the posterior inferior cerebellar artery
were used in all cases. In cases in        (inferior and medial).
which the tumour diameter was larger           After the tumour was removed the
than approximately 2cm, an ultrasonic      dural attachment was removed or
aspirator was used for tumour              coagulated. In two cases the removal
reduction. A facial nerve stimulator       of only a few millimeters of the
was used in all cases to help identify     posterior lip of the IAC was required to
the facial nerve. Preoperative and         remove the entire intracanalicular
postoperative facial nerve functions       portion of the menengioma. In one
and hearing functions were examined        case the tumour occupied the entire
and graded. The mean duration of           IAC and a wide exposure of the IAC
hospitalization was 14.5 days.             was required to reach the fundus.
Neuroimaging Studies                       First the dura mater over the posterior
    Magnetic       resonance     images    aspect of the IAC was removed and the
including contrast-enhanced studies        canal drilled open using small sizes of
had been obtained in all but one           diamond drills until the intrameatal
patient,who had a cardiac pacemaker,       portion was exposed.
and thus high resolution CT scan of the    Patients follow up
petrous bone was performed instead .           All patients underwent follow up
High resolution CT scan was also done      with clinical examination and CT and
for the other cases. MR angiography        or MR images 6 months and one year
was done for 5 cases to assess the         after surgery. Assessment of facial
patency of dural venous sinuses.           never function preoperatively and at
Surgical Procedure                         each postoperative follow up was
    The       standard     retrosigmoid    based on the House - Brackman
approach with the patient in the lateral   grading system 21.
position was used in all cases to
E.J.N.S. Vol. 22 No. 2            June 2007                                         83

An otological examination was                                     RESULTS
routinely conducted in the department
of ENT by performing pure tone                     Clinical data
audiometry and speech discrimination               Our series consisted of 18 patients, 14
testing according to the scale of                  women and 4 men with a mean age of
Gardner and Robertson 17 before                    49.1 years (range 32-61 years).
discharging the patient from the                   Diminution of hearing was the main
hospital.                                          presenting complaint in 11 cases (61%)
                                                   other presenting symptoms are shown
                                                   in Fig (1)




            Accidental

         Facial n. palsy

             Headache

        Trig.neuralgia

            Gait ataxia                                                        ar
                                                                           3-DB 1
               Vertigo

                Tinitus

           .of
        Dim hearing

                         0   10   20   30     40      50     60     70
          Fig.(1) Bar graph showing symptoms at time of initial evaluation.


    Results      of     physical     and           tumour in 5 cases (27.8%) and an en
audiological     assessment     revealed           plaque appearance of the tumour in one
impairment of the eighth cranial nerve             case (5.6%).
in 12 patients (66.7 %), gait ataxia was               Hydrocephalus was not present in
present in 6 cases (33.3%). Facial                 any of our cases, and one case (5.6%)
numbness or a decreased corneal reflex             had gross intrameatal tumour growth,
indicating     fifth    cranial    nerve           with widenening of the IAM noted on
impairment was present in 5 cases                  the lesion side when compared with the
(27.8%). None of our patients had                  other side.
lower cranial nerves or long tract signs.              The mean diameter of the tumours
Neuroradiological investigation                    on MR images was 3.2 cm (range 1.2-
    Typical neuroimaging features of               5.1 cm). One meningioma (5.6%) was
meningiomas         were     seen     on           centred on the IAM, 12 tumours were
preoperative MR images or CT scans                 attached to the dura posterior to the
obtained with or without contrast                  IAM (retromeatal 66.7%), 3 tumours
enhancement. The presence of dural                 originated from the dura anterior to the
tail was noticed in 2 cases (11%),                 IAM (premeatal 16.7%) and 2 tumours
hyperostosis of the petrous bone in 4              (11.1%) were in the suprameatal
cases (22%), calcification within the              portion. Table (1)
E.J.N.S. Vol. 22 No. 2        June 2007                                        84

Table (1): Size comparison for four types of posterior petrous meningiomas
                                  <3 cm            3-4 cm        >4 cm
 Retromeatal                      2                6             4
 Premeatal                        2                1             -
 Suprameatal                      1                1             -
 Centered over theIAM             -                -             1

    The differentiation between this          structures in relation to the tumour
tumour and vestibular schwannoma              where only evident during surgery.
was not obvious in all cases, although        table (2).
less common, typical neuroimaging                 The facial and vestibulocochlear
manifestations     of    a    vestibular      nerves were present as solid nerve
schwannoma, such as widening of the           bundles and were separated from the
IAM due to bone erosion, (one case)           tumour by an arachnoid sheath in 13
cystic degeneration of the tumour (2          patients (72%). In these cases the
cases) or a purely globoid shape of the       nerves could be clearly identified and
tumour without dural attachment (one          protected.
case) has been seen in our cases of               In 5 patients, (27.8%) the facial
CPA meningiomas.                              nerve was incorporated into the
Surgical considerations                       capsule of the tumour and could be
    The direction of displacement of          identified with the aid of a nerve
the          trigeminal,         facial,      stimulating electrode. The nerve was
vestibulocochlear, and lower cranial          anatomically preserved in 3 of these
nerves was predictable, depending on          cases (16.7%). In two patients (11.1%)
the dural origin of the tumour as             with tumours of hard consistency,
demonstrated on preoperative MR               however, preservation of the facial
imaging studies, however the exact            nerve was not anatomically possible.
locations    of    the    neurovascular


 Table (2) Relationship of cranial nerves to the tumours in different locations
Tumour site                  V                 V11 & V111               1X , X & X1
Retromeatal           unrelated 8          Anterior 11               Inferior 6
                      Ant-superior 4       Inferior 1                Unrelated 6

Premeatal             Anterior     3       Posterior 2                Unrelated 2
                                           Inferior 1                 Inferior 1

Suprameatal           Anterior 2           Inferior 2                 Unrelated 2

Centered over the Anterior 1               Anterior 1                 Inferior 1
IAM

   The extent of tumour resection                 A tumour remnant (Simpson Grade
according to the Simpson classification       111) was left in one patient with frank
was Grade 1 in 5 patients (27.8 %),           infiltration of the petrous bone and
Grade 11 in 10 patients (55.6 %),             another patient with infiltration of the
Grade 111 in 2 (11.1%) and G 1V in            seventh-eighth nerve complex. The
one (5.6%).                                   patient of Grade 1V had a premeatal
E.J.N.S. Vol. 22 No. 2        June 2007                                     85

meningioma and tumour extention into           Only two patients in this study had
the Meckel Cave.                           mild       facial      nerve     paresis
    All patients with trigeminal pains     preoperatively, in those patients the
(16.7%) had complete resolution of         facial nerve was adherent to the
their symptoms postoperatively. The        capsule of hard tumours and was not
preoperative hearing level was             preservsd, and they had permanent
preserved in 13 patients (72%) and one     worsening of facial nerve functions.
of them (5.6%) showed mild                     Another 2 patients had temporary
improvement of hearing functions after     facial nerve paresis which resolved
surgery while 5 patients (25.8%)           completley within months post
showed deterioration of hearing            surgery. A new or an aggravated
functions.                                 postoperative gait ataxia was observed
Postoperative Complications                in 5 patients (27.8%), and it has
    The main complication in this          completely resolved in all of them after
study was related to facial and auditory   variable period post surgery.
nerve functions. Deterioration of              A CSF leak from the wound site in
hearing functions was observed in 5        2 cases (11.1%) which was treated
patients      (27.8%)     which     was    using lumbar drainage in one patient
progressive      after   surgery     and   and VP shunt placement in the other,
irreversible.     Four     cases     had   whose postoperative CT scan showed
preoperative hearing impairment, and       hydrocephalus.
one had no preoperative hearing                Wound infection was observed in
deficit. These cases were unrelated to     one case (5.6%) without signs of
the tumour size or location.               meningitis, which was treated with
                                           antibiotics. Table (3)

Table 3:     Postoperative complications in 18 patients with posterior petrous
meningiomas
          Complication                         No of cases           %
 Deteriorated auditory functions            5                  27.8%
 Deteriorated facial nerve functions        4                  22.2%
 Ataxia                                     5                  27.8%
 CSF leak                                   2                  11.1%
 Wound infection                            1                  5.6%




Fig. (2): (A) Axial contrast-enhanced MR image showing atumour medial to the
IAC and compressing the brainstam. (B) Follow up MR image obtained one month
after surgery,demonstrating complete tumour resection.
E.J.N.S. Vol. 22 No. 2      June 2007                                      86




Fig. (3): (A) preoperative T1 contrast-enhanced MR image revealing a postmeatal
meningioma. (B) postoperative CT scan demonstrating complete tumour resection
via a retrosigmoid approach.




Fig. (4): (A) T1enhanced MR image demonstrating a tumour lateral to the IAC. (B)
Follow up T1 enhanced MR image revealing total resection of the tumour.




Fig. (5): Axial (A) and coronal (B) T1 MR images showing a tumour with an
extensive base located at the posterior surface of the petrous bone. (C) Follow up
contrast enhanced CT scan of the same case.
E.J.N.S. Vol. 22 No. 2         June 2007                                        87

           DISCUSSION                           Hearing impairment was the main
                                            presenting complaint and neurological
    Meningiomas are the second most         sign in many series(9,12,24,25-28)
common tumour occupying the CPA                 Hearing loss has been reported to
angle.(13)                                  be present in 60 to 75 % of patients
    Five to eight percent of all            with meningiomas of the CPA. In our
intracranial menengiomas occur in the       study, hearing impairment was
CPA, of these CPA tumours, acustic          detected in 66.7 % of patients.
neuromas comprise 70 to 80%,                Headache was the main symptom and
menengiomas 10 to 15%, and                  gait ataxia was the predominant
epidermoid tumours 4 to 5 %. The            neurological sign in some series,(12) in
remainder are composed of diverse           patients with menengiomas of the
other lesions.(18,22,26)                    jugular fossa, neuropathies of the lower
    Most published series about             cranial nerves occurred in 50 % in
menengiomas of the CPA have focused         another series.(7) In our study, gait
on tumours originating from the dura        ataxia was the presenting complaint in
mater of the petrous bone, the              22.2%, while headache was present in
tentorium, the clivus , and the jugular     16.7%, and none of our patients had
foramen.(4,8,19,24,26,27,28)                neropathies of the lower cranial nerves
    It has been shown that petroclival      because we had no inframeatal
meningiomas constitute a separate           tumours.
entity. These lesions are less frequently       Trigeminal neuralgia affected 18 %
excised totally and are associated with     of the patients in Bassiouni etal
higher surgical morbidity and mortality     series,(12) while it affected 16.7 %of
rates than tumours solely attached to       our cases. Postoperative resolution of
the posterior petrous dura.(6,10,26,27)     this symptom was observed in all but
    In the microsurgical era, morbidity     one patient in Bassiouni et al. series,(12)
and mortality rates in patients with        while Sekhar and Jannetta(26) reported
petroclival meningioma have ranged          resolution of trigeminal neuralgia after
between 31and 50 % and between 0            surgery in all eight patients in their
and 17 %, respectively.(6,10,20)            series. Also we had complete
    Partial resections are common with      resolution of trigeminal pains in all 3
meningiomas in this location whereas        patients in our series (16.7%).
the rate of total removal ranges from           Magnetic resonance imaging is the
25 to 85%.(16)                              diagnostic tool of choice to delineate
    In Bassiouni etal series total          the dural origin of the tumour
removal defined as Simpson Grade 1          preoperatively and to detect tumour
and 11 resection and no visible tumour      extending into the IAM, the jugular
remnant on follow up MR imaging was         foramen or the Meckel cave. However,
achieved in 84.3 % of patients              bone window high-resolution CT
harboring meningiomas whose dural           scanning is more sensitive than MR in
attachment was restricted to the            demonstrating bone changes, such as
posterior surface of the petrous bone.      expansion and erosion of the IAM, in
    The reasons for performing a            cases with gross intrameatal tumour
subtotal resection in their series          extention. Patency of the venous
included invation of the petrous bone,      sinuses can be depicted accurately on
infiltration of functioning cranial         preoperative MR imging or MR
nerves, and tumour extention into the       angiography. Because these tumours
Meckel Cave .                               usually receive their major arterial
                                            blood supply from branches of the
E.J.N.S. Vol. 22 No. 2          June 2007                                       88

meningohypophysial                  trunk,    inferior in 8.4% of them, while these
preoperative embolization of the              nerves were found posterior in 66.7%
tumour was not possible, nor was it           of premeatal tumours and inferior in
believed to be an important adjunct to        33.3% of them. In suprameatal
surgery,12       in      most     patients,   tumours the seventh-eighth complex
preoperative MR imaging study results         was found inferior in all cases.
allow for accurate classification of a            Bao Wu et al(14) advocated another
tumour in relation to the PA,                 classification    system      for   CPA
nonetheless,      there      are   several    meningiomas, according to imaging
limitations, the exact dural origin of        manifestations and intraoperative
the tumour or en plaque extentions            observations. Type 1 posterior petrous
may become visible only during                meningiomas were located lateral to
surgery in some cases . Even on MR            the IAC (34 %) type 11 located
imaging studies it’s usually not              medially to the IAC, which might
possible to demonstrate intimately            extend to the cavenous sinus, (39 %)
involved neurovascular structures             and type 111, extensive attachment to
directly or to drtermine their position       the posterior surface of the petrous
in      relation     to     the    tumour     bone which might envelop the seventh
preoperatively. Tumour consistency            and eighth nerves and extend to the
and the relationship between arachnoid        clivus and supra tentorium (27%).
membranes and tumour surface are                  Samii(2) classified posterior petrous
important determinants for functional         meningiomas into two types: those
preservation        of       neurovascular    anterior to the IAC and those posterior
structures and are recognized only            to the IAC , and most investigators
during surgery. With these limitations        hold the same view.(1,3,5)
in mind, preoperative classification of           Yasargil et al.(6) asserted that
these tumours according to their dural        meningiomas in this region should be
attachment in relation to the IAM gives       classified into anterior petroclival
the surgeon valuable information about        meningiomas and posterior CPA
the most probable dislocation of the          meningiomas.
fifth through 11th cranial nerves.(12)            Schaller, et al.(4) reported on 31
     In the series of Bassiouni etal 12       CPA meningiomas and divided them
the facial-vestibulocochlear nerve            into premeatal and retro- meatal
complex was consistently found on the         meningiomas.
ventral aspect of retromeatal tumours             In meningiomas of the posterior
(84 %) and on the caudal surface of           petrosal surface a lateral suboccipital
supra meatal tumours (70 %). Similar          approach suffices even when the
observations have been described by           tumour is located ventral to the
other investigators.(2,26)                    seventh-eighth nerve complex, all
     Schaller et al.(4) found the seventh-    tumours      in    this    series   were
eighth nerve complex on the lateral           successfully removed using this
(posterior) aspect of 57 % of premeatal       approach. Early drainage of the lateral
tumour. These nerves were separated           cerebellomedullary cistern allowed
from the tumour in 59% of retromeatal         gentle retraction of the cerebellum and
meningiomas and were never found on           direct visualization of the tumour .
the medial (anterior) aspect of the           This approach has been used
tumour.                                       successfully by other investigators of
     In our study the seventh-eighth          CPA meningioma.(2,6,11,26)
nerve complex was found anterior in               Preoperative facial nerve paresis is
91.6% of retromeatal tumours, and             a rare sign (11% in our study) even in
E.J.N.S. Vol. 22 No. 2          June 2007                                       89

patients with large tumours or lesions        subgroups and lowest in those in the
with gross intrameatal extension.             premeatal supgroup. They also
Intraoperatively, the facial nerve can        reported       postoperative      hearing
usually be preserved because it’s             improvement in 8% of their patients.
separated from the tumour surface by          The analysis of the data in their study
the arachnoid membrane. Once the              allowed no prediction in regard to
nerve is identified, the arachnoid is         postoperative hearing function to be
stripped away by using it as a                made in an individual case and every
protective sheath for the nerve during        effort should be made to preserve
further resection. This was observed in       normal        anatomical       structures
the majority of our patients, and facial      subserving auditory functions.
nerve function was preserved in these             Wu Bao et al.(14)            reported
cases (72%). When the arachnoid               deterioration of hearing functions in
membrane has undergone regressive             33% and improvement in 18% of their
changes and is firmly adherent to the         patients. Regarding the extent of
tumour or when the facial nerve               tumour resection, we had residual
courses through the tumour the nerve          tumour in 3 patients (16.7%) meaning
can be detected using a stimulating           Simpson Grade 111 and 1V a tumour
electrode.      Usually        anatomical     remnant was left in cases of frank
preservation       using       meticulous     infiltration of the petrous bone,
microsurgical preparation technique is        infiltration of the seventh-eighth nerve
possible in these cases provided that         complex and extension into the Meckel
the nerve is identified as a single           Cave. Schaller et al.(4) analysed
strand. In two of our patients (11.1%)        meningiomas in the CPA and subtotal
harboring large tumours of hard               resection was performed in 30% of
consistency, the nerve was splayed            their cases, followed by radiotherapy .
over the tumour surface and thus could        Wu Bao et al.(14) reported residual
not      be    preserved.       Permanent     tumour in 17% of their patients to
deterioration of facial nerve function        preserve vital vascular and central
has been reported to be between 7 and         nervous system structures. The residual
30% in the literature(6,12,23,24,26,27) and   tumours left were in the cavernous
was observed in 2 patients in our study       sinus, brain stem, vessels or nerves and
(11%).                                        they recommended gamma knife
     The preoperative hearing level was       therapy after surgery.
preserved in 72.2% of patients in this            Bassiouni et al.(12) did not find any
study, one of them showed mild                recurrent tumours from known tumour
improvement (5.6%) while 5 patients           remnants on infiltrated cranial nerves
(27.8%) showed deteriation of hearing         along 5.4 years follow up period. They
functions which was unrelated to the          concluded that although complete
tumour size or location . Matties et          removal of a tumour including its dural
al.(24) reported on a series of 134           origin should always be the goal of
meningiomas involving the CPA , the           surgery, preservation of infiltrated
retrosigmoid approach had been used           functioning cranial nerves should have
in the majority of their patients and         the priovity, because there are no data
hearing was preserved in 82% and              puplished showing an increased risk of
improved in 6% . Bassiouni etal 12            recurrence from tumour traces on
reported hearing preservation in (69%)        infiltrated nerves.
of their patients. The rate of hearing
preservation was highest in patients in
the suprameatal and retrameatal
E.J.N.S. Vol. 22 No. 2         June 2007                                       90

         CONCLUSIONS                            entities. Acta Neurochir 141 : 465-
                                                471, 1999
    Meningiomas of the CPA require          5. Selesnick SH, Nguyen TD, Gutin
special surgical management. Analysis           PH, Lavyne MH: Posterior
of preoperative MR Images meaning               petrous      face     meningiomas.
the exact dural origin of the tumour in         Otolaryngol Head Neck Surg 124 :
relation to the PA gives valuable               408-413 , 2001
information about the most probable         6. Yasargil MG, Mortara RW,
site of displaced cranial nerves. The           Curcic M: meningiomas of the
exact     relationship     of    critical       basal posterior cranial fossa. Adv
neurovascular structures in relating to         Tech Stand Neurosurg 7 : 1-115 ,
the tumour can only be fully                    1980
appreciated intraoperatively. Hence, a      7. Arnautovic KI, AL-Mefty O:
careful operative technique with                Primary meningiomas of the
familiarity with the anatomy and                jugular fossa. J Neurosurg 97 :12-
effective      intraoperative      nerve        20 , 2002
monitoring are prerequisites to obtain      8. Arriaga M, Shelton C, Nassif P,
an optimal functional result. It’s wise         et al: Selection of surgical
to leave a trace of tumour on infiltrated       approaches      for    meningiomas
but functioning nerves because no               affecting the temporal bone.
recurrence has been observed from               Otolaryngol Head Neck Surg 107 :
these tumour remnants.                          738-744 , 1992
                                            9. Baguley DM, Beynon GJ, Grey
                                                PL, et al: Audio-vestibular
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